The flat display devices have been widely adopted due to the attributes, such as thin, low power-consuming, and no-radiation. The conventional flat display devices may include liquid crystal displays (LCDs) and organic light-emitting displays (OLEDs).
With the development of the technology and the demand by the human, the size of the flat display devices has become greater, the resolution of the display devices has become higher, and the demand for the manufacturing processes has become greater. The large-sized display panels, such as a thin film transistor (TFT)-LCD, may easily have a Mura problem (i.e., uneven brightness problem) due to the defects of the manufacturing processes. Conventionally, the Mura problem may be solved by improving the manufacturing processes. For the portion that cannot be solved by improving the manufacturing processes may be solved by a Demura technique, which is a compensation method for the uneven brightness.
Regarding to the display panels which have been manufactured, the physical properties are determined. The grayscale compensation method may be adopted to correct the brightness of the pixels, so as to compensate for the Mura effect resulting from the defects of the manufacturing processes. The grayscale compensation method is achieved by changing the grayscale value of the pixels to improve the uniformity of the brightness. The grayscale compensation method is to obtain the Mura status of the grayscale image captured by the camera, and the input image is a single grayscale picture (theoretically, the brightness of all pixel is the same), to increase the grayscale value of the darker region by a predetermined compensation value (to increase the brightness), to decrease the grayscale value of the brighter region by a predetermined compensation value (to decrease the brightness) according to the brightness of the central region. That is, the grayscale compensation value is decreased with respect to the brighter pixels, and the grayscale compensation value is increased with respect to the darker pixels. As such, each pixel may have a consistent brightness after conducting compensation method, and the Mura problem may be solved.
However, the conventional Demura technique has a compensational range “N”. That is, for the Mura pixels, the maximum number of the grayscale compensation value, which may be increased or decreased, is “N” (“N” is a natural number). If the grayscale compensation value exceeds the compensational range, the compensation method may not be able to be conducted, which may cause the disqualification (NG) of the panels.